Our research is directed to the computer-implemented solution of such problems as tissue typing, serum screening, specificity definition, survival of haplotypes, and genetic restriction of antibody formation. A new serum screening program, first experimented with last summer, has now been implemented on the PDP 11/34 computer. In addition to screening, it estimates the probability of reaction for weak sera for each antigenic specificity; it does more, but takes longer to run. A new tissue typing program implements an empirical bayesian approach to computing the probability of the presence of antigenic specificities on cells and works well. This program has been extended to approach the specificity definition problem. We are encouraged by current results on DR specificities, and will continue to experiment with the program. The fitness of haplotypes was studied in data gathered in an Amish community in 1973. We were able to establish heterogeneity of fitness (p less than 0.02) for low frequency haplotypes in the community. For the high frequency haplotypes in the community, the null hypothesis of no heterogeneity of haplotype fitness was not rejected (p greater than 0.30). The project to place computer terminals in the laboratories is succeeding. Use of the machine by the researchers in the Immunology division and in Biomathematics is increasing. The NUCLOT program utilizes the paper tape reader on the PDP 11/34 to acquire data from scintillation counter tapes. The program processes the data to provide the basic statistics for the analysis of the experiment. Miscellaneous programs include one to calculate HLA haplotype frequencies from phenotype data, and a small number of statistical programs which are available, some as a result of user efforts.